One of the important parts of a computer network, a firewall is necessary to prevent the unauthorized access to the system. Implementing a firewall is significant to avoid security breach as well as to prevent data corruption that is usually caused by accessing harmful sites. Aside from these, it is also important to filter messages in intranets. To extend our understanding on this special and useful computer architecture, it is best to have a closer look at the functions of this appliance as well as the different kinds of firewall techniques that can be used to enhance the security features of a network.


What is a firewall? A firewall is a special appliance or computer software that is present in a network, which regulates traffic depending on a particular set of rules established by the administrator of the system. This computer software can be used both for filtering communications over the Internet and intranets. To be assured that this device will function well or as expected, the administrator of the system should have sufficient knowledge on the proper configuration of a firewall.

When configuring the device, it is important to have ideas about the standard security practices because these initiate a default-deny rule. The steps involved in firewall configuration need thorough attention from the administrator because these can threaten the day-to-day operations of the system. To successfully configure the software, the administrator should have ample understanding on network endpoints as well as network applications.


To ensure that a firewall will function efficiently, there are some techniques that can be used, which include packet filter, application gateway, circuit-level gateway as well as proxy server. Packet filtering is very efficient because it inspects every packet that enters or leaves the computer network. However, the downside of this technique is that it is prone to Internet Protocol spoofing. Application gateway is another effective technique since it uses security mechanisms in filtering different computer applications like Telnet and FTP servers.

Circuit-level gateway inspects threats related to UDP or TCP connection. However, the disadvantage of this technique is that once a connection was done, packets entering the system are no longer filtered. Proxy server is important to intercept data leaving and entering the network. This technique is effective in concealing the real address of the computer network.

Aside from the techniques, firewalls are also classified into different categories. These categories are important to the efficient functioning of the software. Some of the widely used categories of firewalls are network layer and packet filters, application layer, proxies as well as network address translation.